SMPTE RP 134-1994

This practice specifies the polarity of the signal on the pin connections from a microphone presented with a positive pressure on the diaphragm. It also specifies the resulting positive magnetization when the positive microphone signal is recorded on any magnetic media.

This practice also specifies how this positive magnetization should be played back and fed through a reproducing system to provide a positive sound pressure from the loudspeaker.